As LSI circuits are increasing in density, circuit linewidths required of semiconductor devices are becoming finer year by year. To form a desired circuit pattern on a semiconductor device, a method is used which includes reducing the size of a high-accuracy original pattern (mask or also called a reticle, which is used particularly in a stepper or a scanner) formed on quartz and transferring the reduced pattern to a wafer with a reduced projection exposure apparatus. The high-accuracy original pattern is written through an electron beam writing apparatus by using what is called electron beam lithography technology.
A writing apparatus using multiple beams enables irradiation with many beams at once as compared with writing with a single electron beam, and thus markedly increases throughput. In such a multi-beam writing apparatus, for example, an electron beam emitted from an electron gun passes through a shaping aperture member having a plurality of holes, thus forming multiple beams (electron beams). Under the shaping aperture member, a blanking aperture member is disposed. The blanking aperture member has passage holes aligned with the holes arranged in the shaping aperture member. In each of the passage holes, a blanker is disposed. Each blanker performs blanking deflection on the electron beam passing through the passage hole. The electron beams deflected by the blankers are interrupted. The electron beams that are not deflected by the blankers are applied to a sample.
In the multi-beam writing apparatus, these two aperture members have to be aligned with each other so that beams passed through the shaping aperture member can pass through the passage holes of the blanking aperture member.
In the related art, to allow beams to pass through holes of two aperture members, the center of each of the aperture members and the amount of rotation thereof are measured by use of a coil or a deflector disposed between the aperture members, and alignment is performed based on measurements. However, in a multi-beam writing apparatus including a shaping aperture member and a blanking aperture member arranged close to each other, it is difficult to dispose a mechanism for deflecting beams between these aperture members.
Alignment can be performed by repeatedly moving and rotating a stage holding the aperture members. Disadvantageously, such a way of repeatedly moving the stage requires much time for alignment.